If you copy all of your data onto another drive, you can use any partitioning program to delete the existing partition and create a new one. I like Parted Magic, which uses GParted. You can also install GParted and others in Tiny Core.
I don't know how you use your drive, but you may also consider splitting it up, and also having an Ext3 partition for Linux stuff.
To work, the partition you access from Windows, may need to be the first one.